Design and Synthesis of a Ruthenium (II) Complex-Based Luminescent Probe for Highly Selective and Sensitive Luminescence Detection of Nitric Oxide (original) (raw)
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A unique ruthenium(II) complex, bis(2,2′-bipyridine)(4-(3,4-diaminophenoxy)-2,2′-bipyridine)ruthenium(II) hexafluorophosphate ([(Ru(bpy)2(dabpy)][PF6]2), has been designed and synthesized as a highly sensitive and selective luminescence probe for the imaging of nitric oxide (NO) production in living cells. The complex can specifically react with NO in aqueous buffers under aerobic conditions to yield its triazole derivative with a high reaction rate constant at the 1010 M−1 s−1 level; this reaction is accompanied by a remarkable increase of the luminescence quantum yield from 0.13 to 2.2 %. Compared with organic probes, the new RuII complex probe shows the advantages of a large Stokes shift (>150 nm), water solubility, and a wide pH-availability range (pH independent at pH>5). In addition, it was found that the new probe could be easily transferred into both living animal cells and plant cells by the coincubation method, whereas the triazole derivative was cell-membrane impermeable. The probe was successfully used for luminescence-imaging detection of the exogenous NO in mouse macrophage cells and endogenous NO in gardenia cells. The results demonstrated the efficacy and advantages of the new probe for NO detection in living cells.
A ruthenium(II) complex, [Ru(bpy)2(DA-phen)](PF6)2 (bpy: 2,2'-bipyridine; DA-phen: 5,6-diamino-1,10-phenanthroline), has been developed as a photoluminescent (PL) and electrochemiluminescent (ECL) dual-signaling probe for the highly sensitive and selective detection of nitric oxide (NO) in aqueous and biological samples. Due to the presence of electron transfer process from diamino group to the excited-state of the Ru(II) complex, the PL and ECL intensities of the probe are very weak. After the probe was reacted with NO in physiological pH aqueous media under aerobic conditions to afford its triazole derivative, [Ru(bpy)2(TA-phen)]2+ (TA-phen: 5,6-triazole-1,10-phenanthroline), the electron transfer process was inhibited, so that the PL and ECL efficiency of the Ru(II) complex was remarkably increased. The PL and ECL responses of the probe to NO in physiological pH media are highly sensitive with the detection limits at low micromolar concentration level, and highly specific without the interferences of other reactive oxygen/nitrogen species (ROS/RNS) and metal ions. Moreover, the probe has good cell-membrane permeability, and can be rapidly transferred into living cells for trapping the intracellular NO molecules. These features enabled the probe to be successfully used for the monitoring of the endogenous NO production in living biological cell and tissue samples with PL and ECL dual-modes.
Electrochemiluminescence (ECL) detection technique using bipyridine-ruthenium(II) complexes as probes is a highly sensitive and widely used method for the detection of various biological and bioactive molecules. In this work, the spectral, electrochemical and ECL properties of a chemically modified bipyridine-ruthenium(II) complex, [Ru(bpy)2(dabpy)]2+ (bpy: 2,2′-bipyridine; dabpy: 4-(3,4-diaminophenoxy)-2,2′-bipyridine), were investigated and compared with those of its nitric oxide (NO)-reaction derivative [Ru(bpy)2(T-bpy)]2+ (T-bpy: 4-triazolephenoxy-2,2′-bipyridine) and [Ru(bpy)3]2+. It was found that the ECL intensity of [Ru(bpy)2(dabpy)]2+ could be selectively and sensitively enhanced by NO due to the formation of [Ru(bpy)2(T-bpy)]2+ in the presence of tri-n-propylamine. By using [Ru(bpy)2(dabpy)]2+ as a probe, a sensitive and selective ECL method with a wide linear range (0.55 to 220.0 μM) and a low detection limit (0.28 μM) was established for the detection of NO in aqueous solutions and living cells. The results demonstrated the utility and advantages of the new ECL probe for the detection of NO in complicated biological samples.
Development of a Ruthenium(II) Complex-Based Luminescent Probe for Hypochlorous Acid in Living Cells
A unique ruthenium(II) complex, [Ru(bpy)2(DNPS-bpy)](PF6)2 (bpy: 2,2′-bipyridine, DNPS-bpy: 4-(2,4-dinitrophenylthio)methylene-4′-methyl-2,2′-bipyridine), has been designed and synthesized as a highly sensitive and selective luminescence probe for the recognition and detection of hypochlorous acid (HOCl) in living cell samples. The probe can rapidly and specifically react with HOCl to afford a highly luminescent bipyridine-Ru(II) complex derivative, [Ru(bpy)2(COOH-bpy)](PF6)2 (COOH-bpy: 4′-methyl-2,2′-bipyridyl-4-carboxylic acid), accompanied by the remarkable luminescence enhancement.
Development of a functional ruthenium (II) complex for probing hypochlorous acid in living cells
A functional ruthenium(II) complex, [Ru(bpy)2(AN-bpy)](PF6)2 (bpy: 2,2′-bipyridine, AN-bpy: 4-methyl-4′-(4-amino-3-nitro-phenoxy-methylene)-2,2′-bipyridine), has been designed and synthesized as a turn-on luminescent probe for the imaging of hypochlorous acid (HOCl) in living cells. Due to the intramolecular photoinduced electron transfer (PET), the ruthenium(II) complex itself is almost non-luminescent. However, it can specifically and rapidly react with HOCl in aqueous media to afford a highly luminescent derivative, [Ru(bpy)2(HM-bpy)](PF6)2 (HM-bpy: 4-hydroxymethyl-4′-methyl-2,2′-bipyridine), accompanied by a 110-fold luminescence enhancement. Taking advantage of high specificity and sensitivity, and excellent photophysical properties of the ruthenium(II) complex probe, [Ru(bpy)2(AN-bpy)](PF6)2 was successfully applied to the luminescence imaging of the exogenous HOCl in living HeLa cells and the endogenous HOCl in porcine neutrophils. The results corroborate that indeed [Ru(bpy)2(AN-bpy)](PF6)2 is a useful luminescent probe for the monitoring of HOCl in biological systems.
Developing Red-Emissive Ruthenium(II) Complex-Based Luminescent Probes for Cellular Imaging
Ruthenium(II) complexes have rich photophysical attributes, which enable novel design of responsive luminescence probes to selectively quantify biochemical analytes. In this work, we developed a systematic series of Ru(II)-bipyrindine complex derivatives, [Ru(bpy)3-n(DNP-bpy)n](PF6)2 (n = 1, 2, 3; bpy, 2,2′-bipyridine; DNP-bpy, 4-(4-(2,4-dinitrophenoxy)phenyl)-2,2′-bipyridine), as luminescent probes for highly selective and sensitive detection of thiophenol in aqueous solutions. The specific reaction between the probes and thiophenol triggers the cleavage of the electron acceptor group, 2,4-dinitrophenyl, eliminating the photoinduced electron transfer (PET) process, so that the luminescence of on-state complexes, [Ru(bpy)3-n(HP-bpy)n]2+ (n = 1, 2, 3; HP-bpy, 4-(4-hydroxyphenyl)-2,2′-bipyridine), is turned on. We found that the complex [Ru(bpy)(DNP-bpy)2]2+ remarkably enhanced the on-to-off contrast ratio compared to the other two (37.8 compared to 21 and 18.7). This reveals a new strategy to obtain the best Ru(II) complex luminescence probe via the most asymmetric structure. Moreover, we demonstrated the practical utility of the complex as a cell-membrane permeable probe for quantitative luminescence imaging of the dynamic intracellular process of thiophenol in living cells. The results suggest that the new probe could be a very useful tool for luminescence imaging analysis of the toxic thiophenol in intact cells.
A Novel Ruthenium-based Molecular Sensor to Detect Endothelial Nitric Oxide
Scientific Reports, 2019
Nitric oxide (NO) is a key regulator of endothelial cell and vascular function. The direct measurement of NO is challenging due to its short half-life, and as such surrogate measurements are typically used to approximate its relative concentrations. Here we demonstrate that ruthenium-based [Ru(bpy)2(dabpy)]2+ is a potent sensor for NO in its irreversible, NO-bound active form, [Ru(bpy)2(T-bpy)]2+. Using spectrophotometry we established the sensor’s ability to detect and measure soluble NO in a concentration-dependent manner in cell-free media. Endothelial cells cultured with acetylcholine or hydrogen peroxide to induce endogenous NO production showed modest increases of 7.3 ± 7.1% and 36.3 ± 25.0% respectively in fluorescence signal from baseline state, while addition of exogenous NO increased their fluorescence by 5.2-fold. The changes in fluorescence signal were proportionate and comparable against conventional NO assays. Rabbit blood samples immediately exposed to [Ru(bpy)2(dabpy...
Inorganica Chimica Acta, 2015
The chemical properties of the trinuclear ruthenium complex [Ru 3 O(CH 3 COO) 6 (3-pic) 2 (NO)]PF 6 (1, were 3-pic = 3-picoline or 3-methylpyridine), its photochemical behavior and its ability as a vasorelaxing agent are reported in this work. It was shown that the unpaired electrons of NO and of the metal center [Ru 3 O] + are tightly coupled, promoting an intermediate NMR profile between the oxidized (paramagnetic) and reduced (diamagnetic) [Ru 3 O] 1+/0 species. From IR measurements, it was suggested that in trinuclear complexes, unlike other ruthenium compounds, the interaction of those unpaired electrons overcomes the effect of peripheral ligands and NO-backbonding on the m(NO) frequency, which shows no dependence on the pK a values of pyridinic ligands. The photoinduced NO release was investigated by light irradiation at 337, 447, 532 and 660 nm in phosphate buffer solution (pH 7.4), leading to the generation of gaseous NO 0 and the solvated species [Ru 3 O(CH 3 COO) 6 (3-pic) 2 (H 2 O)] + (2). Through amperometric and quimioluminescence measurements, the amount of NO(g) released were determined, showing dependence on the wavelength of irradiation. The ability of compound 1 as a vasorelaxing agent was also addressed. It was shown that, under ambient luminosity, compound 1 promotes 89% of relaxation in pre-contracted rat aorta. Molecular modeling of the novel nitrosyl, as well as characterization of the complexes [Ru 3 O(CH 3 COO) 6 (3-pic) 2 (L)] n , L = H 2 O, n = +1 (2), L = 3-pic, n = +1 (3), L = CO, n = 0 (4), are also reported.
Inorganica Chimica Acta, 2013
Novel ruthenium nitrosyl complex [Ru(g 1-L 1)(PPh 3) 2 (NO)Cl 2 ] (2) (where L 1 H is 3-chlorobenzoic acid and H is dissociable proton) was synthesized and characterized by spectroscopic and electrochemical studies. Molecular structure of complex 2 was determined by X-ray crystallography. The diamagnetic behaviour of 2 was established by NMR spectral studies and redox property of 2 was investigated. DFT optimization of the structure of 2 provided a linear geometry of {Ru II-NO + } moiety. The nitrosyl complex acted as novel nitric oxide (NO) donor upon illumination of light and photoreleased NO was trapped by reduced myoglobin. Amount of photolytically cleaved NO was quantified by Griess reagent. The precursor complex [Ru(g 2-L 1)(PPh 3) 2 Cl 2 ] (1) was obtained after photorelease of NO and was found to be a potential NO scavenger. Flipping of denticity of carboxylate ligand was observed during NO donation and scavenging. DPPH (2,2-diphenyl-1-picrylhydrazine) radical quenching assay was performed to estimate the amount of generated reactive nitrogen species or/and reactive oxygen species during photolysis of NO.
The Journal of Physical Chemistry B, 2007
The photochemical behavior of the tetraazamacrocyclic complex trans-RuCl([15]ane)(NO) 2+ (RuNO 2+) in a 10 mM phosphate buffer solution, pH 7.4, and in the presence of Ru(NH 3) 5 pz 2+ (Rupz 2+) is reported. Irradiation (436 nm) of an aqueous solution containing both cationic complexes as PF 6salts labilizes NO from RuNO 2+ with a quantum yield (φ NO) dependent on the concentration of Rupz 2+ with a maximum value of φ NO (1.03(11) × 10-3 einstein mol-1) found for a solution with equimolar concentrations (5 × 10-5 M) of the two complexes in phosphate buffer solution. The quantitative behavior of this system suggests that the two cations undergo preassociation such that photoexcitation of the visible absorbing Rupz 2+ is followed by electron or energy transfer to RuNO 2+ , which does not absorb appreciably at the excitation wavelength, and this leads to NO release from the reduced nitrosyl complex. Notably, the NO release was not seen in the absence of phosphate buffer; thus, it appears that phosphate ions mediate NO generation, perhaps by facilitating formation of a supramolecular complex between the two ruthenium cations. Reexamination of the cyclic voltammetry of Rupz 2+ showed that the electrochemical behavior of this species is also affected by the presence of the phosphate buffer.